1. Field of the Invention
The present invention relates to a vertical shaft impact crusher for crushing ores and minerals, more specifically a vertical shaft impact crusher that is self-lubricating without the need of pumps for cooling and lubrication.
2. Prior Art
Vertical shaft impact crushers are well known in the art as a useful and effective means to crush ores and minerals for various uses including aggregate for concrete, paving stones, as well as many other uses.
A problem associated with the continuous use of vertical shaft impact crushers is the need to keep the rotating shaft bearings lubricated while at the same time preventing excessive heat buildup within the crusher and/or shaft housing. Various attempts have been made to remedy these concerns. Most crushers use conventional oil-lubrication systems which use filters to remove dirt and a pump to circulate the oil. These systems are subject to bearing failure in the event the pump malfunctions. Other lubricating systems have been disclosed in U.S. Pat. No. 4,560,113 to Szalanski (use of a grease injection system to lubricate the bearings) and U.S. Pat. No. 1,405,151 to Overstrom (using an axial bore inside the vertical shaft to lubricate the bearings). However, no reference discloses the use of at least one propeller on the outer surface of the shaft inside the shaft housing to provide a driving force for circulation of the lubricant as the shaft rotates. No reference discloses positioning the lubricant reservoir such that the hydraulic pressure associated with the height of the lubricant in the reservoir can be used to aid in the circulation and thermal cooling of the lubricant. Furthermore, no reference discloses using the combination of propellers on the shaft and hydraulic pressure of the lubricant itself to aid in the cooling and circulation of the lubricant.
In offshore platform drilling operations, a by-product of drilling operations is drill cuttings, which are the rock, mineral and other subterranean materials that are cut away by the drill from the well bore as the well is drilled. These materials are brought to the surface in the drilling fluid and drilling mud. A common problem that drilling companies face is the disposal of these materials because many of the drill cuttings produced from the drilling operations are deemed hazardous wastes by the United States Environmental Protection Agency ("USEPA") and various state environmental agencies. Disposal of these materials can be expensive, especially for offshore platform drilling operations where the material must be transported back to shore for proper disposal. Recent USEPA regulations have been passed which allow the drill cuttings to be placed back down hole if certain particle size requirements are met.
While the recent USEPA regulations allow the drill cuttings to be placed back downhole, there exists a need for an apparatus or method which will crush the drill cuttings on site and allow disposal of the crushed cuttings downhole, thereby allowing drilling companies to comply with the USEPA regulations without transporting the drill cuttings elsewhere for processing and/or disposal. The need is greater for offshore drilling platforms because it is very expensive to transport the drill cutting onshore to be crushed and shipped back to the offshore platforms for disposal in accordance with the new USEPA regulations.
A major concern for offshore drilling platforms is the amount of weight which can be placed on the platform itself. While conventional crushers are often bulky and heavy, the present invention is designed to fit on an offshore drilling platform while taking up a minimum amount of space and adding little weight to the offshore platform. As stated earlier, many of the conventional vertical shaft impact crushers use a pump to circulate the lubricant. While it may be conventional to use a pump for lubricant circulation, the use of a pump in a vertical shaft impact crusher on an offshore drilling platform presents several problems. First, during continuous drilling operations, the malfunction of the pump in the vertical shaft impact crusher will prevent the continuous disposal of the drill cuttings, thereby causing expense and delay. Second, in the event of a pump malfunction, a back-up pump must be available on the offshore platform at all times. The addition of two pumps, when not otherwise needed, adds additional weight on the offshore drilling platform. The present invention eliminates the lubricant pump, thereby eliminating all the concerns that offshore drilling platform operators would face should they choose to crush and dispose of the drill cuttings at the offshore drilling platform itself.